Add the client for accessing Subresource Filter only list.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 05ece5a71fcc4cdcf1b6adbab524412d063cc8d9..6e3205d91680a350c3a0173f1080517de78a6211 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -66245,12 +66245,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="SubresourceFilter.PageLoad.RedirectChainLength" units="urls">
   <owner>melandory@chromium.org</owner>
+  <suffix name="SubresourceFilterOnly"/>
   <summary>Total length of the server redirects during the navigation.</summary>
 </histogram>
 
 <histogram name="SubresourceFilter.PageLoad.RedirectChainMatchPattern"
     enum="SubresourceFilterMatchPattern">
   <owner>melandory@chromium.org</owner>
+  <suffix name="SubresourceFilterOnly"/>
   <summary>
     For each main frame navigation, records a pattern that indicates which URLs
     in the redirect chain matched Safe Browsing blacklists, and which did not.